The paper describes a virtual furnace for fire-resistance tests following standard fire conditions. The model takes advantage of great possibilities of computational fluid dynamics code Fire Dynamics Simulator. The model is based on an accurate representation of a real fire furnace of fire laboratory PAVUS a.s. located in the Czech Republic. It includes geometry of the real furnace, material properties of the furnace linings, burners, ventilation conditions and also a tested specimen with measurement devices. The model allows controlling of gas temperature and the static over pressure in the volume of the furnace as it is specified in requirements of European standard for fire resistance tests. The accuracy of the model is validated to a fire test of empty horizontal furnace executed in the fire laboratory, which was except other carried out to harmonize initial settings of burners in the model. Then, the virtual furnace is used to investigate thermal behaviour for fireresistance test of a steel beam. The results of the virtual furnace illustrate the great potential for investigating the thermal behaviour of fire-resistance tests.

Purpose This paper aims to present a part of a coupled numerical model for prediction the fire resistance of elements in a horizontal furnace. Temperatures calculated inside the timber beam are compared to measured values from the fire test. Design/methodology/approach The paper presents a part of a coupled numerical model for prediction the fire resistance of elements in a horizontal furnace. The presented part lies in a virtual furnace which simulates temperature environment around tested elements in the furnace. Comparison of results show good agreement in the case when burning of timber is included in the numerical model. Findings The virtual furnace presented in this paper allows to calculate temperature environment around three timber beams. After validation of the fire dynamics simulator (FDS) model, the temperature conditions are passed to the FE model which solves heat transfer to the tested element. Temperatures inside the timber beam which are solved in software Atena Science are compared to measured temperatures from the fire test. The comparison of temperatures in three control points shows good accuracy of the calculation in the point closer to the heated edge. An inaccuracy is shown in points located deeper in the beam cross-section – below the char layer. Research limitations/implications In conclusion, the virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions. However, passing the temperature field from the FDS model into FE model may decrease the level of accuracy. The solution lies in a coupled CFD-FE model. A weakly coupled model including fluid dynamics, heat transfer and mechanical behaviour is under development at Faculty of Civil Engineering, Czech Technical University in Prague. The fluid dynamics part which is presented in this paper is solved by FDS and the thermo-mechanical part is computed by object-oriented finite element model (OOFEM). The interconnection of both software is made owing to MuPIF python library. Practical implications The virtual furnace takes advantage of great possibilities of computational fluid dynamics code FDS. The model is based on an accurate representation of a real fire furnace of fire laboratory PAVUS a.s. located in the Czech Republic. It includes geometry of the real furnace, material properties of the furnace linings, burners, ventilation conditions and tested elements. Gas temperature calculated in the virtual furnace is validated to temperatures measured during a fire test. Social implications The virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions. Originality/value The virtual furnace has a great potential for investigating the thermal behaviour of fire-resistance tests. A huge advantage inheres in the evaluation of the thermal effect throughout the volume of the furnace, which allows an accurate prediction of fire-resistance tests and evaluation of large number of technical alternatives and boundary conditions. However, passing the temperature field from the FDS model into FE model may decrease the level of accuracy. The solution lies in a coupled CFD-FE model. A weakly coupled model including fluid dynamics, heat transfer and mechanical behaviour is under development at Faculty of Civil Engineering, Czech Technical University in Prague. The fluid dynamics part which is presented in this paper is solved by FDS and the thermo-mechanical part is computed by OOFEM. The interconnection of both software is made thanks to MuPIF python library.

This paper is focused on a comparison of zone fire modelling software tools and their application in structural fire design. The analysis of the zone models is performed for five selected computer programs, namely Argos, Branzfire, B-RISK, CFAST, and OZone. The limits and input parameters ofthe zone fire modelling software tools are described. In each software, two variants of the analysed compartment are created for simulating two types of fire scenario, including the fuel-controlled fire and the ventilation-controlled fire. The burning regimes are defined based on two heat release rate(HRR) curves, determined according to EN 1991-1-2. The HRR curves parameters are used as the main input data into the fire modelling software. The fire simulation method in each fire modelling software is selected based on the software capabilities. Although each program requires a different amount of input parameters, the aim was to create the same model in all programs and to compare the results. The fire modelling software outputs are exported into a spreadsheet. Subsequently, a comparison of the resulting graphs is performed, particularly the heat release rate graphs and the upper layertemperature evolution graphs. The fire resistance assessment of a simply-supported concrete slab panel is performed for all zone fire models and then the results are compared. The fire modelling software tools are finally quantitatively and qualitatively evaluated and compared to assess their differences.

The paper deals with the analysis of fire resistance of concrete structural members exposed to fire based on different fire models. An illustrative example of the assessment of a slab panel is presented. Several fire models are employed in order to predict the evolution of temperature in a selected fire compartment. Some of these fire models, namely the ISO fire curve and the parametric fire curve, are implemented in an in-house MATLAB code. For the more comprehensive fire models, external scientific software tools are used, namely the CFAST software for the zone model and the FDS software for the CFD (computational fluid dynamics) model. By employing the results of the fire simulations, the fire resistance of the slab panel is assessed. It is performed by a one-way coupled numerical procedure based on a well-known heat transfer finite element model and iterative sectional mechanical analysis. The procedure is implemented in an in-house MATLAB code. It is shown that (i) the numerical procedure can be employed in connection with different fire models and (ii) the fire resistance prediction can be strongly influenced by the type of selected fire model.

The paper is focused on the fire model parameter variability and its effect on the determination of fire resistance of concrete structural members.For the modelling of fire, the parametric temperature-time curve given in EN 1991-1-2 is used.First part of the paper is aimed on the fire model parameter variability in general.First, fire model parameter ranges are described and their combinations are created using two common sampling methods -- Monte Carlo and Latin Hypercubes.Then, the combinations are analysed, unreasonable combinations are identified, and viable combinations are illustrated.Moreover, the characteristics of the temperature-time curves obtained using the parameter combinations are discussed. Namely, we focus on the temperature evolution, duration of fire, andthe maximum temperature reached.In the second part of the paper, an illustrative example is presented.The example is focused on the analysis of the fire resistance of a concrete slab panel. The panel is placed in a fire compartment with given fire model parameter ranges. In the example, the variability of the fire model parameters is captured using the Latin Hypercubes sampling method.The thermal analysis of the slab panel as well as the subsequent mechanical analysis are both conducted by using numerical methods described in our previous work. The calculations are performed in MATLAB environment.Finally, the obtained results are presented and discussed.It is shown that the Latin Hypercube sampling can be used as an effective tool for the investigation of the effect of fire model parameter variability on the fire resistance.